Starting device fob electric motobs



0. 8. JENNINGS. smnme DEVICE FOR ELECTRIC MOTORS.

APPLICATION FILED JUNE 511916- Patented Sept. 16, 1919.

WITNESSES ATiORNEY ing windings are employed to assist in protion butit' necessitates a special construction of the primary core member andfurther-' mined s eeds.

OLIVER 8. JENNINGS, OI WILKINSBUBG, ASSIGNOB TO WEST- INGHOUSE ELECTRICAND PENNSYLVANIA.

KANUI'AOTUBING COMPANY, A CORPORATION OF s'rm'rme mwrcn m nmc'rmcmorons.

Specification of Letters Patent.

Patented Sept. 16, 1919.

Application fled June 5, 1916. lerlal No. 101,728.

To all whom it may concern Be it known that I, OLIVER a citizen of theUnited States, and a resident of Wilkinsburg, in the county of Alleghenyand State of Pennsylvania, have invented a new and useful Improvement inStarting Devices for Electric Motors, of which'the following. is aspecification.

My invention relates to electric motors,

and particularly to single-phase inductionand similar motors in whichauxiliary startducin suflicient torque during the starting period.

The object of my invention is to provide simple and efi'ective means forinterrupting the circuit of the starting winding of an induction motor,or for otherwise rendering the starting means ineffective when the motorattains a predetermined speed.

Single-phase induction motors are usually provided with auxiliarystarting windings of relatively high resistance so that it is desirableto interrupt the circuits of such windings when the motors obtainpredeter- The means heretofore employed or this pur se have usually beenoperated by centri ugal force and consequently have been complicatedand'expensi-ve in construction and more or less unreliable in operation;Centrifugally-actuated' devices of this character are particularly un-,

reliable when used in connection with motors operating at relatively lowspeeds, such, for example, as motors driving ceilin fans. In Patent'No.934,466,

Company, there is shown and described a device for interruptin thecircuit of the starting winding of an lnduction motor, the operation ofwhich is dependent upon the tion of the secondary member. This devicecomprises in general a magnetizabla armature or keeper embedded in theprimary core member and adapted to control the circuit of the startingwinding. This device has been found to be quite satisfactory in opera-S. J nnnmos,

grantd'to M. Scheibe on Sept. 21, 1909, and assigned to the WestinghouseElectric & Manufacturing primary winding..3.

more cannot be readily embodied in motors .already in service.

According to the present invention, I ro-- vide a sin le-phase motorwith an auxiliar winding, in addition to the starting win mg, which isadapted to operate a suitable relay device and thereby control thecircuit of the starting winding. The auxiliary winding is so-arrangedwith res ct to the primary and starting windings o the motor that thevoltage induced therein by the resultant flux in the primar core membershall be substantially a minimum when the motor is at rest and shall besubstantially a maximum when ghe motor reachesthe speed at which it ismost desirable to interrupt the circuit of the starting winding.Consequently, the voltage induced in the auxiliary winding is a.function of the slip of the motor and is dependent upon the cross-fluxproduced in the primary core member by the reaction of the secondarymember.

In the accompanying drawings, Figure 1 is a diagrammatic view of asingle-phase motor embodying my invention and showing the connections ofthe relay device'for' controlling the circuit of the starting winding;Fig. 2 is a view, similar to Fig. 1, showing a modific tion of the relaydevice; and Fig. 3 is a developed view of the motor winding showndiagrammatically in Fig. 1.

Themotor comprises relatively rotatable magnetlzable members 1 and 2which are provided with a primary winding 3, a startmg winding 4 and anauxiliary winding 5 and a. secondary winding 6, respectively.

As shown best in Fig. 3,.the primary core member 1 isprovided with aplurality of -slots 7 and teeth 8. The main winding 3 and thestartingvwinding 4 are so distributed in the slots 7 that there are sixteeth per pole for each winding. The windings 3 and 4 are so arrangedwith respect to each other that the magnetic axes of the poles producedby the starting winding 4 are displaced sub stantially ninety electr caldegrees from the I e auxiliary winding 5 is arranged to produce poles ofunlike polarity of the windings 3 magnetic axesof the pales produced bythe and 4.

I Referring tan-Fig.1, the main winding a poles intermediate is adaptedto bummed to'a suitable a connected to' the conductor 11 through thestationary contact. member 13 and a movable contact member 14 of a relaydevice 15. The relay device 15 further com rises an armature '17 and awinding 16 t at is connected to the terminals of the auxiliary windin5.- The armature 17 is pivotally connec to the contact member 14 by aspindle 18 that extends through the core 19 of the relay. The armature17 is normall held away from the core 19' by a spring 20, ereby in thecontact members-13 and 14 in closed ation and completing the circuit ofthe starting winding 4 with the source 9.

Having fully described the winding and circuit connections of the motor,the operation of in device is as follows. The prienergized from thesource 9 through the onductors 10, 11 and'12 and the nor mally closedcontact members 13 and 14, the motor starts as a split-phase motor, aswill be readily understood. At'the moment of start the resultantmagnetic field produced y the prima 3 and the starting winding 4 in ucesa voltage in the auxiliary winding 5. The value of this voltage is verysma as the auxiliary winding is so distributed in the slots-that themag- .netic fields produced by the main and start- -ing windings tend tosubstantially neutralize each other with respect to theauxiliarywinding. The direction of current flow' in rated, opzningthecircuit ofthe 'necte'd .that it is east 20 tends to hold thewindings is indicatedby arrows in Fig. 8. As the speed of the motor increases, a

tpmroduced the reaction of. t e secondary cross-flux is age m theauxiliary winding. The ,relay 15 isso'designed that when the motorreaches a predetermined the total voltage in-- .-ducedintheau the coil16 sufliciently to cause the armature- 17 to be drawn toward the core18. The coniary winding 5 energizes taet members 13 and 14 will thenbO'NPB.

A modification of the relay device is shown in F 2 wherein the-relay iswound difierenti y. One "winding 16 is-conne'cted across theterminals ofauxiliary winding 5 and an opposing winding 21 is so conrea the PMmenses 14 apart but as soon-as the winding 21is "'energized the armature17 is'drawn toward the core 19 to close the contact members,

thereby completin'gthe of the startugh conductors mamtainlgary win ing 3and the starting winding 4' rimary core ing winding 4. When the motorreaches a predeterminedspeed, the vol the auxiliary wmding 5 energizesthe relay winding 16 which neutralizes the effect of the relay winding21. The spring 20 then retracts the armature 17 and 0 us the contactmembers 13 and 14, there y interruptmglthe circuit ofthe startingwinding 4. It m be readily understood t at by using the differentiallywound relay, all tendency for thearmature-l'! to chatter will beeliminated by the neutralizing efiect of the windings 21 and 16,Furthermore, the operation'of the relay device is positive and certain,as it is entirely dependent upon the production of a voltage in theauxiha winding.

While I have shown my mvention as applied to a particular type ofinduction motor,,it is not so limited but may be as readily applied toall motors operating on the same general principle and in connectionwith various other relay devices and I desire that onlysuch limitationsshall be imposed thereon as may tall within'the scope of the appendedclaims. I claim as my invention:

1. Inan electric motor, the combination with relatively rotatableprimary and secondary members,.a stamng win ried by said primary member'an auxiliary winding carri 'by said primary memher and adapted toenergized by the crowflux produced. in'sald primary member the reactionof said secondary member, of a 'out upon the energlzation of saidauxiliary w nding, and lay forrendenng the said w mefl'ective when thecross-flux attams a pre determined value.

an motor ,the combgxgiion W1 primary an secondary mm a main winding, isstarting winding carried 'by said prima member and an auxiliary wincarri by said primary member and a pted tobe bythe crusaflux in'saidprimary member, o tial rela device for controlling said startingwinding, the operation of which is dependent upon theonergization ofsaid main and a I p In eectric motor, the combination .ew th p andmembers, a carr ed by sai d primary member and annmnliary windingpartied by sa d membirand to be snags e.cross- In m as: nmary A of' a rel a de vlifie for control! 5.1 8km!!! p' eration :i which is depen dentqplon the energ'ization ofi said and aux: 'ary windii ua a m winding me!1711 fi fective when-the voltage induced m and means controlled .=bysaid areby. said relay a.

induced in dmgcar-' auxiliary winding by the cross-flux attains apredetermined value. 4. In an electric niotor,,the combination withrelatively rotatable magnetizable members respectively provided with aprimary winding and a 'seconda squirrel-cage winding, and a start' wmdito produce a magnetic eld disp aced from that produced by the primarywindmgs, of an auxiliary winding mterlinked with said primary andstarting windings and so arranged that the voltage induced therein is afunction of the flux produced b the reaction of said primary and seconary memhem. V

5. In an electric motor, the combination with relatively rotatablemagnetizable memarranged bers provided with rimary and seconda windings,respective y, and a startingwin ing arranged to produce a ma displacedfrom that produced-by the primary winding, of an auxiliary windinginterlinked with said primer and starting windings and so arranged t atthe voltage induce therein by the flux traversin the primary member'shall be substantial a minimum when the motor starts and sha be a.maximum when the motor reaches a prede termined speed.

In testimony whereof I have hereunto subscribed my namethis 27th day ofMay,

OLIVER s. JENNINGS.

gnetic field

